The Nittany Lions held Purdue scoreless in a 1-0 road win.
McFayden will join the squad after Seifarth's exit.
The mass exodus of recruits continues following James Franklin's firing.
Allar is expected to make a full recovery ahead of Penn State's Pro Day.
Franklin will make first public appearence since his firing on national televison.
Cerrato joins Mac Gadowsky and Aiden Fink on a star-studded roster.